Fix the CCW bug and add Altitude in LoiterN Dialog
LoiterN Bug fix

1. Fix CCW checkbox keep on resetting when reopening LOITER_N dialong
box.
2. add '-' to waypoint list when slectin non NAV command such as RTL,
GO_TO etc.
3, Fix bug Delay not updated in Waypoint Dialog
Making home marker un-draggable, and if invalid  then invisible.

This closes #233
Refactoring some common code.
Merge pull request #289 from arthurbenemann/HomeFix

Home fix
Merge pull request #287 from azrin1972/WPLoiterTAltitude

Waypoint Loiter N bug fixes